emotional, which is the coolest. you meet a person and right away you feel like you've known them forever and could tell them all of your secrets.

the second is intellectual, which is basically when you find someone as smart as you are and with whom you can talk to about various subjects that you are both familiar with. boring, really, but worth mentioning.

the third and final level is the physical one. from the very first time you touch the other person, being just a brush of a hand or a hug, you feel electric sparks jumping between you and every nerve in the affected area becomes tingly. this is not based on appearance, it's a rare occurance. in fact, all three of these are rare occurances and you should consider yourself lucky to have ever experienced them.